1st Fresnel Zone Radius & 60% Obstruction-Free Line-of-Sight Clearance Calculator

Compute 1st Fresnel Zone midpoint radius (m), 60% clearance zone, and 4/3-Earth bulge.

1st Fresnel Zone Midpoint Radius (F₁)
10.17 meters
60% Obstruction-Free Clearance Radius 6.1 meters
4/3-Earth Curvature Bulge at Midpoint 0.94 meters
Total Midpoint Tower Clearance Needed 7.04 meters
Inputs
⚡ Scenarios:
km
Total point-to-point link distance D in kilometers.
GHz
Operating RF frequency in GHz (e.g., 0.915, 2.4, 5.8, 11, 24 GHz).
Results & Graph
1st Fresnel Zone Midpoint Radius (F₁)
10.17 meters
60% Obstruction-Free Clearance Radius
6.1 meters
4/3-Earth Curvature Bulge at Midpoint
0.94 meters
Total Midpoint Tower Clearance Needed
7.04 meters

1st Fresnel Zone Midpoint Radius (F₁)

Graph 1 • Fresnel Zone Clearance • Domain Architecture & Live Telemetry Maps Total Link Distance Km, Frequency Ghz through Fresnel Zone Clearance Formula.
Source / Tx Target / Rx Fresnel Zone Clearance Propagation Path 1st Fresnel Zone Midpoint 10.17 meters 60% Obstruction-Free Clear: 6.1 meters 4/3-Earth Curvature Bulge : 0.94 meters
Graph 2 • 1st Fresnel Zone Midpoint Radius (F₁) Across Total Link Distance Km Sweep (40% → 160%) Evaluates F₁_midpoint (m) = 8.656 × √( TotalDistance_km / Frequency_GHz ); Clear across 7 operating points (current input highlighted).
0 meters 7.07 meters 14.15 meters 6.43 3.20km 7.87 4.80km 9.09 6.40km 10.17 8km 11.14 9.60km 12.03 11.20km 12.86 12.80km
Graph 3 • Joint Sensitivity: Total Link Distance Km × Frequency Ghz Compares 1st Fresnel Zone Midpoint Radius (F₁) when Frequency Ghz is shifted +25% (solid) vs. −25% (dashed).
0 meters 7.36 meters 14.72 meters --- Frequency Ghz @ 75% 7.61 -30% 8.38 -15% 9.09 +0% 9.75 +15% 10.37 +30%
Summary: Over 8 km at 5.8 GHz, the 1st Fresnel Zone midpoint radius is 10.17 m; maintain at least 6.1 m (60% F₁) plus 0.94 m Earth curvature bulge = 7.04 m total clearance above obstacles.
Summary: Over 8 km at 5.8 GHz, the 1st Fresnel Zone midpoint radius is 10.17 m; maintain at least 6.1 m (60% F₁) plus 0.94 m Earth curvature bulge = 7.04 m total clearance above obstacles.
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Formula & Mathematical Methodology: Fresnel Zone Clearance Formula

F₁midpoint (m) = 8.656 × TotalDistancekm / FrequencyGHz
Clearance60% = 0.60 × F₁
F₁_midpoint (m) = 8.656 × √( TotalDistance_km / Frequency_GHz ); Clearance_60% = 0.60 × F₁
  • totalLinkDistanceKm: Total Link Distance Km (km)
  • frequencyGhz: Frequency Ghz (GHz)

Rounding: Engineering outputs round to 2–3 decimal places; discrete material bag/unit counts round up via ceiling.

Worked Example: Engineering Scenario: Fresnel Zone Clearance

Compute 1st Fresnel Zone midpoint radius (m), 60% clearance zone, and 4/3-Earth bulge.

  1. Enter your system dimensions, electrical/RF ratings, or environmental conditions.
  2. Evaluate the governing equation: F₁_midpoint (m) = 8.656 × √( TotalDistance_km / Frequency_GHz ); Clearance_60% = 0.60 × F₁.
  3. Inspect the primary design output, supporting allowances, and 3 SVG schematics.
Result: Computes Fresnel Zone Clearance via F₁_midpoint (m) = 8.656 × √( TotalDistance_km / Frequency_GHz ); Clearance_60% = 0.60 × F₁.

Frequently Asked Questions

How does the 1st Fresnel Zone Radius & 60% Obstruction-Free Line-of-Sight Clearance Calculator calculate results?

It evaluates F₁_midpoint (m) = 8.656 × √( TotalDistance_km / Frequency_GHz ); Clearance_60% = 0.60 × F₁ directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a required dimension or rating?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Does this engineering calculator work offline?

Yes. All calculations run 100% locally in your browser and work offline via the CalculatorGraph PWA.

Science & Engineering · RF, Telecom & Antenna Engineering

1st Fresnel Zone Radius & 60% Obstruction-Free Line-of-Sight Clearance Calculator: inputs, method, and how to read the result

Compute 1st Fresnel Zone midpoint radius (m), 60% clearance zone, and 4/3-Earth bulge.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Total Link Distance Km: Total point-to-point link distance D in kilometers.
  • Frequency Ghz: Operating RF frequency in GHz (e.g., 0.915, 2.4, 5.8, 11, 24 GHz).

What the calculation includes

With the default values shown, 1st Fresnel Zone Midpoint Radius (F₁) is 10.17 meters. The calculation follows Fresnel Zone Clearance Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Total Link Distance Km from 8 km to 9 km changes 1st Fresnel Zone Midpoint Radius (F₁) from 10.17 meters to 10.78 meters. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard NREL, IEEE, ASHRAE, and IRC design equations.
  • Verify final structural, electrical, and mechanical specifications against local building codes.

Scope: Global Engineering & Building Code Standard Check the assumptions and limitations against your situation before relying on the estimate.

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